Everything Solar Forum

First off, where are you? Regulations vary based on location. Second, PV panel load is widely distributed across an area. A typical 41 x 62" panel (~17sqft) weighs 40 Lb. That's approx. 2.4Lb per sqft, which is frankly nothing. A double or triple shingled roof has more total load. Most res construction is designed for a minimum of 20 Lb per sqft. In reality a res roof can easily hold 50 Lb per sqft, though that is not necessarily a good load for 100% duty cycle, etc... warping, etc..

12" of wet snow weighs approx. 13 Lb sqft. 2 feet would be 26 Lb. sqft. etc..

Another practical data point is how old is the roof? 5 years or 50 years. 2x6 or 2x8 or 2x10 roof rafters, pitch, etc.. all effect downward pressure and structural load points. The steeper the roof the more load is shifted to the exterior walls off the center, and so on....

So 2.4, IF IT WERE ME, I would tell him to go pound sand.... but that's just blunt me....

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william fitch
Owner
www.WeAreSolar.com
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Thank you, william.

I'm in northern California. The house was built in 2006. The roof is in very good condition. Basically, we don't have snow load here. The sales agent keeps saying they are a large company and trying to do good work. Just wanted to know whether I can make a claim against this comapny. 

First off, where are you? Regulations vary based on location. Second, PV panel load is widely distributed across an area. A typical 41 x 62" panel (~17sqft) weighs 40 Lb. That's approx. 2.4Lb per sqft, which is frankly nothing. A double or triple shingled roof has more total load. Most res construction is designed for a minimum of 20 Lb per sqft. In reality a res roof can easily hold 50 Lb per sqft, though that is not necessarily a good load for 100% duty cycle, etc... warping, etc..

12" of wet snow weighs approx. 13 Lb sqft. 2 feet would be 26 Lb. sqft. etc..

Another practical data point is how old is the roof? 5 years or 50 years. 2x6 or 2x8 or 2x10 roof rafters, pitch, etc.. all effect downward pressure and structural load points. The steeper the roof the more load is shifted to the exterior walls off the center, and so on....

So 2.4, IF IT WERE ME, I would tell him to go pound sand.... but that's just blunt me....

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william fitch
Owner
www.WeAreSolar.com

That does not look like a really low pitch, like 3/12 or something. No snow than you are left with wind loads and rain loads. I get the feeling that the 7K$ is already gone. If true, that will be messy trying to recover unless "local" laws have allot of leeway.

There is a reason why the old adage, "buyer beware" is what it is....

Thank you, william.

I'm in northern California. The house was built in 2006. The roof is in very good condition. Basically, we don't have snow load here. The sales agent keeps saying they are a large company and trying to do good work. Just wanted to know whether I can make a claim against this comapny. 

First off, where are you? Regulations vary based on location. Second, PV panel load is widely distributed across an area. A typical 41 x 62" panel (~17sqft) weighs 40 Lb. That's approx. 2.4Lb per sqft, which is frankly nothing. A double or triple shingled roof has more total load. Most res construction is designed for a minimum of 20 Lb per sqft. In reality a res roof can easily hold 50 Lb per sqft, though that is not necessarily a good load for 100% duty cycle, etc... warping, etc..

12" of wet snow weighs approx. 13 Lb sqft. 2 feet would be 26 Lb. sqft. etc..

Another practical data point is how old is the roof? 5 years or 50 years. 2x6 or 2x8 or 2x10 roof rafters, pitch, etc.. all effect downward pressure and structural load points. The steeper the roof the more load is shifted to the exterior walls off the center, and so on....

So 2.4, IF IT WERE ME, I would tell him to go pound sand.... but that's just blunt me....

------------------------------
william fitch
Owner
www.WeAreSolar.com

In Ohio we don't generally see concrete tile roofs. But in your area, where they are common, solar can be installed without replacing the roof as long as the structure is designed to handle the added weight of the solar array, which as William said is generally around 2.5lb/sq ft distributed. The installer may have to remove some tiles in order to install the array, because roof hooks are someties attached to the sheathing/framing below the tiles, and the tiles replaced afterward.  Or there may be some mounts that can be installed by drilling through the concrete tile and then adding a flashing to the penetration.  It sounds to me like the company just changed the method they wanted to use to mount the array, like maybe they lost their employees that know how to work with concrete tiles?  I would not think there is any regulation that prevents solar to be installed with tile roof made from 9.7 lb/sq ft tiles. The best time to question all this was before you paid any money to have the array added. Your $7k is likely gone.